Demokit: Scrolling in the API Reference is CPU intensive

[moreRGB]

What is the issue and how can we reproduce it?

Dear SAP Team, thank you for the awesome work on openUI5. Some of our colleagues are using older windows laptops, where this issue is really noticable. Other colleagues usually have an android tablet as a second device to display docs. For many pages like MDN it is not an issue, but for the demokit it is one.

1. Open the sample: https://sdk.openui5.org/api/sap.ui.base.ManagedObject
2. Open your OS resource monitor like task manager. You can also use the chrome profiler.
3. Scroll down or up
4. Even on high performance machines you notice that it is sluggish and slow

Suspected Problem:

Set a event listener breakpoint in chrome for Control - "scroll"
This ends in ObjectPageLayout.prototype._onScroll. Please check this function. It does an absurd amount of processing on each tiny bit of scrolling. It might run hundred times per second, without any deferring/throttling and most of the time it just does nothing.

I have no idea how to fix this, just maybe an recommendation to use IntersectionObservers for the lazy loading parts.

Which OpenUI5 version is your project targeting?

Unrelated / 1.140

Is the issue device- or browser-specific?

Tested with Chrome on Android 15 with Samsung S25 Ultra, Chrome on Chromebook, Chrome on S4 Tablet, Chrome on an Lenovo IdeaPad and also Chrome on Macbook.

Confirmation

• I have searched the existing issues and reviewed the relevant documentation as well as the API reference.
• I am not disclosing any internal or sensitive information.

[dobrinyonkov]

Hi @moreRGB,

Thanks for reporting this and for providing the background and devices tested.

On our side, we haven’t been able to reproduce the sluggish scrolling. To investigate further, could you provide:

• Chrome Profiler data capturing the scroll performance in your scenario.
• The specifications of the laptops where you see the issue (CPU, memory, model, OS version).

This will help us understand whether this is device-specific or something in the implementation.

Thanks!
Dobrin

[moreRGB]

Thank you very much @dobrinyonkov for taking all three Issues so fast. I really appreciate it.

I will try to follow up on this in the next week in the office

Have a nice weekend!